1. Field of the Invention
The present invention relates to medical devices, and more particularly to an expanding vascular stent that is inserted into a blood vessel in the human body and expands the blood vessel, where it is improved in terms of structure to enhance its performance, compared with conventional stents.
2. Background of the Invention
A stent is an artificial tube inserted into a conduit in the human body, such as a blood vessel, etc., to hold the conduit open. The stent is shaped as a cylindrical hollow. The stent is inserted into a blood vessel, etc., opens a strangulated portion and holds it open.
First, the stent needs a high expansion force to hold its cylindrical hollow shape. Second, it is preferable that the stent is as small as possible in the lengthwise and radial directions when it is initially expanded in the radial direction. Third, the stent requires a large degree of flexibility so that it does not damage the blood vessel wall or a balloon catheter when being inserted into a zigzagged blood vessel.
In order to faithfully follow the conditions described above, research and development have been performed using conventional stents. According to US FDA guidelines, when a stent is initially expanded in the radial direction, the change in the length and radius of the stent is restricted to 5˜7%. In particular, they treat the expansion of the stent in the radial direction as an important factor.
A great deal of research has been conducted on conventional stents conforming to the conditions described above, which were disclosed in Korean Patent Publication No. 10-2004-0075346, U.S. Pat. Nos. 7,326,241 and 7,442,203. For example, they have disclosed stents having the same cells being regularly repeated.